I don't own the velours, I MAY buy them eventually, but I'm honestly more interested in testing the angled hybrid or a focuspad/A first. The Angled velour will prob measure a good deal different than the vegan. Velour is def different than micro-suede, the Hm5 are also smaller pads and squishier than the vegans. the HM5 may block the driver outlet a tiny tiny bit at the top and bottom. My advice for the moment is stick to stock or go vegan, unless you want to play around. I am still enjoying the more lively sound signature of the Pleather HM5 though, but pleather feels gross to me. If any one has like any spare pads they would like measured I would be very happy to do so to collect a body of information in the thread, and would ship them back promptly.
if I follow @cskippy
's reasoning correctly, the reason to swap for vegan pads is to reduce the internal/chamber reflection that messes up the higher frequencies from the stock pleather.
discovered the smaller pleather chamber of the angled HM5 pads also smoothed out the higher frequencies (less spikes/dips)
now my reasoning, between perforated pleather (hm5 hybrids) and velour, I think velour is closer to microsuede, so basically, going the angled velour HM5 pads gets the benefits of both cskippy (less reflective surface) and mrtie84's (smaller chamber) theories XD
and FWIW, I added a 3" disc of plain copy paper (your typical office letter sized copying paper) behind the 3" paper towel disc, and yuck, that made sound more closed and echo-y.
then I tried two 3" paper towel discs per each driver, and it gives similar result to adding the extra copy paper disc, tho not as crazy.
so I'll settle the just one 3" paper towel disc for now, all hail @cskippy